BOSTON -Now the hearts and hopes of New England ride on Pedro Martinez, who has been both the worst enemy and best friend of the Yankees.

The Impossible Comeback is one game away from being DOA.

Tonight, the ultimate grudge match -Yankees vs. Red Sox -resumes, with the AL East a longshot prize for Boston following last night’s unconscionable 9-7 loss to Baltimore.

Martinez, who uncharacteristically bucked the saddle on Sunday at Yankee Stadium, has Boston’s fate in his hands tonight. Red Sox fans will be apoplectic if Martinez comes up short against Mike Mussina again.

The Sox dropped to 4½ games behind the Yanks because of a disappointing late-game collapse last night. The wild card is virtually secured, but Boston wants to at least give the Bombers something to think about heading into the postseason.

“Luster’s probably never lost in this series,” said Jason Varitek, who was at his cantankerous best following a loss that dampened the Boston clubhouse.

Manager Terry Francona took the blame for protecting “A-List” relievers Keith Foulke, Mike Timlin and Alan Embree. Instead, Ramiro Mendoza and Mike Myers couldn’t hold a 5-5 tie, as the Orioles went ahead on Jose Leon’s two-run pinch-hit single with two outs in the eighth.

The Orioles piled on two more runs off the recently activated Byung-Hyun Kim in the ninth before a futile Boston rally.

Asked if he felt Boston would have won had he managed differently, Francona answered, “Possibly.”

Before Boston’s series finale with Baltimore last night, various Red Sox players broke out a special T-shirt. The front of the shirt read, “The Time is Now.” On the back was the familiar phrase, “Cowboy Up.”

But Derek Lowe, who also spit the bit in The Bronx, produced a lousy five-inning start -including a three-run homer by Miguel Tejada -and left trailing, 5-2.

The Red Sox tied the score in the fifth with a bases-loaded walk to David Ortiz and a two-run single by Captain Cowboy, Kevin Millar.

Trailing by four in the ninth, the relentless Sox brought the winning run to the plate following Manny Ramirez’s two-run single. But Ortiz flew out to right, about 20 feet short of the bullpen, preventing a third straight walk-off victory.

“We’re in a good situation, we’re in good shape,” Ortiz said. “The people who have to worry are the ones behind us.”

Down 10½ games on Aug. 15, the Sox beat Mariano Rivera last Friday to close within 2½ games. But they lost the next two games and flushed a golden opportunity, partly because Martinez was all too fallible during a five-plus inning, eight-run outing on Sunday.

Obviously, his teammates don’t want a repeat. “I expect him to shut them out,” Johnny Damon said. “I expect him to go out there and win. . . . We won’t be happy with anything less.”

Martinez was preoccupied all weekend with a Post headline that called him “the man N.Y. loves to hate” because of his propensity to hit Yankees, but he didn’t pitch inside. The diminutive Dominican hasn’t been the same against the Bombers since June 20, 2000.

Before then, he was 5-2 with a 2.40 ERA in eight games. In 19 regular-season games since, he’s 5-7 with a 3.48 ERA.

Asked if he expects Martinez to rise to the challenge, Ortiz said, “Hell yeah.”